When I first power on, the screen is black for 8 seconds and then an underline cursor appears. The computer sits idle like this until about 1 minute and 28 seconds when suddenly it starts booting the OS (on flash). So first why is it just sitting there doing nothing for a whole minute and a half and second why is there is no BIOS screen?
For me it is a lot faster, like 10 seconds maximum to fully boot into desktop, also it shows the Udoo logo the whole time. What operating system are you trying to boot? Also try resetting to defaults in the BIOS
@ OP That long delay should/could only happen once when BIOS/UEFI is first-time detection hardware configuration and store such configuration data into the NVRAM. This would happen (onece) also, when you just flash a new version of BIOS. If you see such behavior happens repeatedly, most likely the RTC battery is low. Replacing the battery would solve the issue.
The problem is specific to the presence of a usb flash drive at boot. If there is no flash drive and the computer is set to boot from NVMe, then it boots fine. I suspect this is a bug in the BIOS.